Tubular sucker rods



June 26, 1962 H. DUNBAR 3,040,673

TUBULAR SUCKER RODS Filed Jan. 25, 1960 2 Sheets-Sheet 1 Huey DunbarInventor June 26, 1962 H. DUNBAR TUBULAR SUCKER RODS 2 Sheets-Sheet 2Filed Jan. 25, 1960 FIG. 3

Inventor Huey Dunbar By% Attorney United States Patent Jersey ProductionResearch Company, a corporation of Delaware Filed Jan. 25, 1960, Ser.No. 4,305

7 Claims. (Cl. 103-179) This invention relates to well pumping equipmentand more particularly to well pumping equipment for deep wells. Itrelates especially to a system of pumping a deep well by using hollowsucker rods.

In pumping oil wells it is a common practice to suspend a string oftubing from the surface of the earth to a point below the level of theoil in the well and to reciprocate a plunger within and near the bottomof the tubing by means of a long line of sucker rods extending throughthe tubing and motivated by a power unit at the surface of the earth. Itis obvious that a well may attain such depth that the strain on thesucker rods Will reach a value in excess of the tensile strength of therods, entailing parting or rupture of the rod. When the sucker rodsbreak, a great expense and loss of time is incurred in replacing thebroken rods.

Accordingly an important object of this invention is to reduce thestrain on a string of sucker rods so as to minimize breakage thereof.

It is another object of this invention to provide a system whereby theeffective weight of the long line of sucker rods on a pumping unit atthe surface is reduced. 'An'additional object of the invention is toprovide a system so that larger bore pumps can be set deeper to producehigher volumes of fluid than is possible with any conventional suckerrods.

These and other objects and details of the invention will be apparentfrom the following description, when read in connection with theaccompanying drawings; wherein:

FIG. 1 illustrates, partly in section, a part of an oil well equippedwith pumping means and tubular sucker rods embodying features of theinvention;

FIG. 2 is a horizontal section on the line Z-Z of FIG. 1; and

FIG. 3 illustrates a different embodiment showing a diflerent pumpingmeans.

Referring to the drawing, casing 10, lining the well, is illustrated asset in the top portion of producing reservoir 12. Casing hasperforations 14 so that oil may flow from the reservoir 12 into theinterior of casing 10.

Suspended within casing 10 is tubing 16. Tubing 16 extends from thesurface of the earth to near the bottom of casing 10 or below the liquidlevel of the oil in casing 10 to be pumped to the surface.

A string of hollow sucker rods 18 is suspended within tubing 16.Conventional pumping equipment (not shown) at the surface of the earthis provided to reciprocate sucker rods 18 in the tubing.

Suspended at the lower end of tubing 16 is working barrel 20. Adapted toreciprocate within working barrel 20 is piston 22 which is provided withupper piston ring 24 and lower piston ring 26. Within piston 22 ispassage 28 having check valve 30 which is of a character to prevent thedownward flow of fluid through passage 28. The lower end of workingbarrel 20 is enclosed by plate 32. Bottom plate 32 of working barrel 20has passage 34 with check valve 36 which is of a character to permit oilto flow from the casing into the working barrel but prevents oil flowingdownwardly through passage 34.

In a preferred embodiment hollow sucker rod 18 has a connecting member38 attachable to piston 22 by a lock nut 23. Member 38 is preferablysolid and has a reduced cross section from that of hollow rod 1-8. Apack- 3,040,673 Patented June 26, 1962 ing means is provided in thelower end of tubing 16 to seal the space between connecting member 38and the inner walls of tubing 16. Although there are many ways ofproviding this sealing means it can conveniently be done as illustrated.A packing recess 42 is provided in upper end plate 40 of 'working barrel20. Packing 44 is placed in packing recess 42 and is held there bybushing 46. It is thus seen that an elongated annular reservoir 47 isformed in tubing 16 above the sealing means and the exterior of hollowsucker rod 18.

Passageway 50 with check valve 49 is provided in plate 40. Passageway 50established fluid communication between the interior of working barrel20 above piston 22 and the annulus between tubing 16 and casing 10.

Although not necessary, check valve 49 may be installed in passageway 50to permit fluid to flow out of working barrel 20 through passageway 50but prevent it entering therethrough.

An annulus packer 52 seals the annulus between working barrel 20 andcasing 10 at a position below the outlet of passageway 50. Many wellknown conventional packers are available which are suitable for thisuse.

A liquid 54 is retained in reservoir 48 to at least partially sustainthe weight of hollow sucker rod 18. The liquid should have as high aspecific gravity as possible to add buoyancy to hollow sucker rod 18.The specific gravity of the liquid should preferably exceed 1.00. Liquid54 should further be noncorrosive to the tubing or hollow sucker rods.The liquid also should not contain settleable solids. A suitable liquidis a solution of potassium carbonate in water. In a specific example,potassium carbonate was added to distilled water in the proportion ofabout 616 grams of potassium carbonate per 500 milliliters of Water. Thegravity of this solution at F. was 1.53.

In the operation of this apparatus, tubing 16 (with hollow sucker rod 18suspended therein and pumping means suspended at the lower end of thetubing in a manner similar to that illustrated in FIG. 1) is loweredwithin a well to the fluid to be produced. Annulus packer 52 is then setbelow the outlet of passageway 50. Liquid 54 is then used to at leastpartially fill reservoir 48. Pumping operations are then begun byreciprocating sucker rod 18 by a conventional pumping unit at thesurface of the earth. Oil then flows from reservoir 12 throughperforations 14 and into casing 10 below annulus packer 52. The oil thenflows into working barrel 20 through passage 34 and check valve 35. Onthe down stroke of piston 22 oil flows upwardly through passage 28through check valve 30 and into the space above piston 22 in workingbarrel 20. On the upstroke of piston 22, oil above piston 22 is forcedthrough passageway 50 and check valve 49 and thence up the annulusbetween tubing 16 and casing 10 to the surface of the earth.

It is thus clear that at least partial flotation of the hollow suckerrod is effected, and that the use of a high specific gravity fluidincreases v the effect of flotation. Therefore, the use of a hollowsucker rod system of this invention permits the setting of and use oflarger pumps at greater depths than is possible with conventional suckerrods.

The use of this invention materially reduces the weight on the suckerrods and gravity of about 1.30 in tubing 16. It can be readilycalculated that buoyancy will support 91% of the weight of the rod thusleaving only 9% to be supported at the top. The stretch of the suckerrod due to its own weight is likewise reduced. The design of a hollowrod for a particular job will depend upon many factors such as the depthfrom which fluid is to be pumped, the rate'of pump ing, the nature ofthe fluid to be produced and the density of the liquid. I

FIG. 3 illustrates another embodiment of the invention using afull-opening retrievable pump unit. Parts in FIG. 3 which are identicalto parts in FIG. 1 will be given the same reference numerals. Theillustrated full-opening retrievable pump unit includes the pump barrel56 mounted in the lower end of tubing 57. This is held in place by abottom lock holddown means including an expanding nose 58 and areceiving recess 60' in the lower interior of tubing 57. For adescription of an API bottom lock holddown, reference is made toContinental-Emsco Company illustrations on page 1421, volume I of the23d (1958-1959) revision of the composite catalog published by WorldOil, PO. Box 2608, Houston, Texas. A pump piston 62 is attached toconnecting member 3-8 by locknuts 64. The upper end of pump barrel 56 isclosed by plug 66 which has an aperture 68 therethrough for the passageof connecting rod 38. Sealing means 70 effects a sliding and sealingrelationship between connecting mem ber 38 and cap 66. The lower end ofpump barrel 56 is enclosed by a lower cap 72 having a passage 74therethrough. A check valve 76 is located in passageway 74 and permitsthe flow of fluid only in an upwardly direction therethrough.

As shown piston 62 has a passage 78 vertically therethrough. Passage 78has check valve 80 which permits the flow of fluid upwardly throughpassageway 78 but prevents its flowing downwardly therethrough. Packer52 seals the annulus between tubing'57 and casing 10. Ports 82 and 84 inthewalls of pump barrel 56 and tubing 57 respectively provide fluidcommunication between the upper interior of pump barrel 56 and theannulus between casing and tubing 57. An internal recess 88 in tubing 57serves to interconnect ports 82 and 84 so that exact alignment of theports is not essential. Sealing means 90 above ports 84 and 82 provide asealing relationship between the upper end of pump barrel 56 and tubing57. Another sealing-means 9-2 provides a-fluid-type seal between thelower end of pump barrel 56 and tubing 57.

In the embodiment shown in FIG. 3 if it is desired to remove pump barrel56 for any reason such as repair of check valve, seals, etc., it is seenthat the pump barrel 56 may be removed therefrom without removing orpulling tubing string 57. An upward pull on tubing 18 while tubing 57 isheld stationary results in piston 62 being pulled upwardly against plug66. Further upward movement of pump rods 18 causes expanding nose 58 tobe compressed and move out of recess 60. The pumping unit then may bepulled to the surface for repairs.

It will be noted that the foregoing description is concerned with twostructural embodiments of the invention. It is possible to produce stillother embodiments without departing from the inventive concept hereindisclosed, and it is desired therefore that only such limitation beimposed on the impending claims as are stated therein.

What is claimed is:

1. A well pumping apparatus comprising a combination of a string oftubing, means forming an elongated reservoir in said tubing, a string ofhollow sucker rods reciprocably and sealingly extending longitudinallythrough said reservoir, a high density liquid in said reservoir to putbuoyancy upon said rods, pumping means reciprocable by said hollowsucker rods to pump fluid upwardly from the bottom of the well exteriorof said tubing to the surface of the earth.

2. A pumping apparatus for removing oil from a well comprising a casingin said well, a tubing string suspended within said casing, a hollow rodsuspended'reciprocally in said tubing, packing means disposed in thelower part of said tubing sealingly engaging the inner wall of saidtubing and slidably andsealingly engaging said rod, an annulus packersealingly engaging said tubing and said casing, pumping means suspendedat the lower end of said tubing string below said packer andconnected'to the lower end of said rod, and of a character to pump oilfrom below said annulus packer to above said annulus packer, and aliquid within said tubing above said packing means.

3 An apparatus as defined in claim 2 in which the liquid is a solutionof potassium carbonate in water.

4. An apparatus for pumping liquid from a Well comprising a casing, atubular member suspended within said casing, a hollow sucker rodreciprocable within said tubular member, means forming a liquidreservoir within said tubular member and exterior of said rod, anannulus packer between the lower end portion of said tubular member andsaid casing, pumping means reciprocable by said rod which sealing'lyextends through the bottom of said means for forming a liquid reservoir,said pumping means being further characterized in having its suctionside below said annulus packer and its discharge side in the annulusbetween said casing and said tubular member above said annulus packer,and a liquid within said reservorr.

5. An apparatus as defined in claim 4 in which the specific gravity ofthe liquid is greater than 1.00.

6. An apparatus of the character described for pumping fluid from a wellbore comprising an elongated reservoir suspended within said well bore,a liquid in said reservoir, a hollow rod reciprocably mounted within theliquid in said reservoir, an extension rod connected to the lower end ofthe hollow rod and extending in a sealing and sliding relationshipthrough the bottom of said reservoir, said extension rod sealing thelower end of the hollow rod, pumping means supported at and from thelower end of said reservoir including a piston mounted in said pumpingmeans connected to and motivated by the reciprocation of said rods andconduit means from the discharge side of said pumping means extending tothe surface of the earth.

7. An apparatus as defined in claim 6 in which the liquid is a solutionof potassium carbonate and water.

References Cited in the file of this patent UNITED STATES PATENTS1,900,588 Scott Mar.'7, 1933 1,906,933 Standlee- May 2, 1933 2,051,089Lamb Aug. 18, 1936 2,797,642 Bloudoff' July 2, 1957

